<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>尺寸范围</title>
  
  <style>
    div {
      width: 300px;
      height: 50vw;
      background-color: pink;
    }
  </style>

</head>
<body>
  <div>div标签</div>
</body>
</html>